The Experts below are selected from a list of 77079 Experts worldwide ranked by ideXlab platform
Lourens Poorter - One of the best experts on this subject based on the ideXlab platform.
-
hydraulics and life history of tropical Dry Forest tree species coordination of species drought and shade tolerance
New Phytologist, 2011Co-Authors: Lars Markesteijn, Frans Bongers, Lourens Poorter, Horacio Paz, Lawren SackAbstract:Summary • Plant hydraulic architecture has been studied extensively, yet we know little about how hydraulic properties relate to species’ life history strategies, such as drought and shade tolerance. The prevailing theories seem contradictory. • We measured the sapwood (Ks) and leaf (Kl) hydraulic conductivities of 40 coexisting tree species in a Bolivian Dry Forest, and examined associations with functional stem and leaf traits and indices of species’ drought (Dry-season leaf water potential) and shade (juvenile crown exposure) tolerance. • Hydraulic properties varied across species and between life-history groups (pioneers vs shade-tolerant, and deciduous vs evergreen species). In addition to the expected negative correlation of Kl with drought tolerance, we found a strong, negative correlation between Kl and species’ shade tolerance. Across species, Ks and Kl were negatively correlated with wood density and positively with maximum vessel length. Consequently, drought and shade tolerance scaled similarly with hydraulic properties, wood density and leaf Dry matter content. We found that deciduous species also had traits conferring efficient water transport relative to evergreen species. • Hydraulic properties varied across species, corresponding to the classical tradeoff between hydraulic efficiency and safety, which for these Dry Forest trees resulted in coordinated drought and shade tolerance across species rather than the frequently hypothesized trade-off.
-
Seasonal variation in soil and plant water potentials in a Bolivian tropical moist and Dry Forest
Journal of Tropical Ecology, 2010Co-Authors: Lars Markesteijn, José Iraipi, Frans Bongers, Lourens PoorterAbstract:Abstract:We determined seasonal variation in soil matric potentials (ψsoil) along a topographical gradient and with soil depth in a Bolivian tropical Dry (1160 mm y−1 rain) and moist Forest (1580 mm y−1). In each Forest we analysed the effect of drought on predawn leaf water potentials (ψpd) and drought response (midday leaf water potential at a standardized ψpd of −0.98 MPa; ψmd) of saplings of three tree species, varying in shade-tolerance and leaf phenology. ψsoil changed during the Dry season and most extreme in the Dry Forest. Crests were drier than slopes and valleys. Dry-Forest top soil was drier than deep soil in the Dry season, the inverse was found in the wet season. In the moist Forest the drought-deciduous species, Sweetia fruticosa, occupied Dry sites. In the Dry Forest the short-lived pioneer, Solanum riparium, occupied wet sites and the shade-tolerant species, Acosmium cardenasii drier sites. Moist-Forest species had similar drought response. The Dry-Forest pioneer showed a larger drought response than the other two species. Heterogeneity in soil water availability and interspecific differences in moisture requirements and drought response suggest great potential for niche differentiation. Species may coexist at different topographical locations, by extracting water from different soil layers and/or by doing so at different moments in time.
-
carbohydrate storage and light requirements of tropical moist and Dry Forest tree species
Ecology, 2007Co-Authors: Lourens Poorter, Kaoru KitajimaAbstract:In many plant communities, there is a negative interspecific correlation between relative growth rates and survival of juveniles. This negative correlation is most likely caused by a trade-off between carbon allocation to growth vs. allocation to defense and storage. Nonstructural carbohydrates (NSC) stored in stems allow plants to overcome periods of stress and should enhance survival. In order to assess how species differ in carbohydrate storage in relation to juvenile light requirements, growth, and survival, we quantified NSC concentrations and pool sizes in sapling stems of 85 woody species in moist semi-evergreen and Dry deciduous tropical Forests in the rainy season in Bolivia. Moist Forest species averaged higher NSC concentrations than Dry Forest species. Carbohydrate concentrations and pool sizes decreased with the light requirements of juveniles of the species in the moist Forest but not in the Dry Forest. Combined, these results suggest that storage is especially important for species that regenerate in persistently shady habitats, as in the understory of moist evergreen Forests. For moist Forest species, sapling survival rates increased with NSC concentrations and pool sizes while growth rates declined with the NSC concentrations and pool sizes. No relationships were found for Dry Forest species. Carbon allocation to storage contributes to the growth-survival trade-off through its positive effect on survival. And, a continuum in carbon storage strategies contributes to a continuum in light requirements among species. The link between storage and light requirements is especially strong in moist evergreen Forest where species sort out along a light gradient, but disappears in Dry deciduous Forest where light is a less limiting resource and species sort out along drought and fire gradients.
-
light dependent leaf trait variation in 43 tropical Dry Forest tree species
American Journal of Botany, 2007Co-Authors: Lars Markesteijn, Lourens Poorter, Frans BongersAbstract:Our understanding of leaf acclimation in relation to irradiance of fully grown or juvenile trees is mainly based on research involving tropical wet Forest species. We studied sun–shade plasticity of 24 leaf traits of 43 tree species in a Bolivian Dry deciduous Forest. Sampling was confined to small trees. For each species, leaves were taken from five of the most and five of the least illuminated crowns. Trees were selected based on the percentage of the hemisphere uncovered by other crowns. We examined leaf trait variation and the relation between trait plasticity and light demand, maximum adult stature, and ontogenetic changes in crown exposure of the species. Leaf trait variation was mainly related to differences among species and to a minor extent to differences in light availability. Traits related to the palisade layer, thickness of the outer cell wall, and Narea and Parea had the greatest plasticity, suggesting their importance for leaf function in different light environments. Short-lived pioneers had the highest trait plasticity. Overall plasticity was modest and rarely associated with juvenile light requirements, adult stature, or ontogenetic changes in crown exposure. Dry Forest tree species had a lower light-related plasticity than wet Forest species, probably because wet Forests cast deeper shade. In Dry Forests light availability may be less limiting, and low water availability may constrain leaf trait plasticity in response to irradiance.
Lars Markesteijn - One of the best experts on this subject based on the ideXlab platform.
-
hydraulics and life history of tropical Dry Forest tree species coordination of species drought and shade tolerance
New Phytologist, 2011Co-Authors: Lars Markesteijn, Frans Bongers, Lourens Poorter, Horacio Paz, Lawren SackAbstract:Summary • Plant hydraulic architecture has been studied extensively, yet we know little about how hydraulic properties relate to species’ life history strategies, such as drought and shade tolerance. The prevailing theories seem contradictory. • We measured the sapwood (Ks) and leaf (Kl) hydraulic conductivities of 40 coexisting tree species in a Bolivian Dry Forest, and examined associations with functional stem and leaf traits and indices of species’ drought (Dry-season leaf water potential) and shade (juvenile crown exposure) tolerance. • Hydraulic properties varied across species and between life-history groups (pioneers vs shade-tolerant, and deciduous vs evergreen species). In addition to the expected negative correlation of Kl with drought tolerance, we found a strong, negative correlation between Kl and species’ shade tolerance. Across species, Ks and Kl were negatively correlated with wood density and positively with maximum vessel length. Consequently, drought and shade tolerance scaled similarly with hydraulic properties, wood density and leaf Dry matter content. We found that deciduous species also had traits conferring efficient water transport relative to evergreen species. • Hydraulic properties varied across species, corresponding to the classical tradeoff between hydraulic efficiency and safety, which for these Dry Forest trees resulted in coordinated drought and shade tolerance across species rather than the frequently hypothesized trade-off.
-
Seasonal variation in soil and plant water potentials in a Bolivian tropical moist and Dry Forest
Journal of Tropical Ecology, 2010Co-Authors: Lars Markesteijn, José Iraipi, Frans Bongers, Lourens PoorterAbstract:Abstract:We determined seasonal variation in soil matric potentials (ψsoil) along a topographical gradient and with soil depth in a Bolivian tropical Dry (1160 mm y−1 rain) and moist Forest (1580 mm y−1). In each Forest we analysed the effect of drought on predawn leaf water potentials (ψpd) and drought response (midday leaf water potential at a standardized ψpd of −0.98 MPa; ψmd) of saplings of three tree species, varying in shade-tolerance and leaf phenology. ψsoil changed during the Dry season and most extreme in the Dry Forest. Crests were drier than slopes and valleys. Dry-Forest top soil was drier than deep soil in the Dry season, the inverse was found in the wet season. In the moist Forest the drought-deciduous species, Sweetia fruticosa, occupied Dry sites. In the Dry Forest the short-lived pioneer, Solanum riparium, occupied wet sites and the shade-tolerant species, Acosmium cardenasii drier sites. Moist-Forest species had similar drought response. The Dry-Forest pioneer showed a larger drought response than the other two species. Heterogeneity in soil water availability and interspecific differences in moisture requirements and drought response suggest great potential for niche differentiation. Species may coexist at different topographical locations, by extracting water from different soil layers and/or by doing so at different moments in time.
-
light dependent leaf trait variation in 43 tropical Dry Forest tree species
American Journal of Botany, 2007Co-Authors: Lars Markesteijn, Lourens Poorter, Frans BongersAbstract:Our understanding of leaf acclimation in relation to irradiance of fully grown or juvenile trees is mainly based on research involving tropical wet Forest species. We studied sun–shade plasticity of 24 leaf traits of 43 tree species in a Bolivian Dry deciduous Forest. Sampling was confined to small trees. For each species, leaves were taken from five of the most and five of the least illuminated crowns. Trees were selected based on the percentage of the hemisphere uncovered by other crowns. We examined leaf trait variation and the relation between trait plasticity and light demand, maximum adult stature, and ontogenetic changes in crown exposure of the species. Leaf trait variation was mainly related to differences among species and to a minor extent to differences in light availability. Traits related to the palisade layer, thickness of the outer cell wall, and Narea and Parea had the greatest plasticity, suggesting their importance for leaf function in different light environments. Short-lived pioneers had the highest trait plasticity. Overall plasticity was modest and rarely associated with juvenile light requirements, adult stature, or ontogenetic changes in crown exposure. Dry Forest tree species had a lower light-related plasticity than wet Forest species, probably because wet Forests cast deeper shade. In Dry Forests light availability may be less limiting, and low water availability may constrain leaf trait plasticity in response to irradiance.
Frans Bongers - One of the best experts on this subject based on the ideXlab platform.
-
hydraulics and life history of tropical Dry Forest tree species coordination of species drought and shade tolerance
New Phytologist, 2011Co-Authors: Lars Markesteijn, Frans Bongers, Lourens Poorter, Horacio Paz, Lawren SackAbstract:Summary • Plant hydraulic architecture has been studied extensively, yet we know little about how hydraulic properties relate to species’ life history strategies, such as drought and shade tolerance. The prevailing theories seem contradictory. • We measured the sapwood (Ks) and leaf (Kl) hydraulic conductivities of 40 coexisting tree species in a Bolivian Dry Forest, and examined associations with functional stem and leaf traits and indices of species’ drought (Dry-season leaf water potential) and shade (juvenile crown exposure) tolerance. • Hydraulic properties varied across species and between life-history groups (pioneers vs shade-tolerant, and deciduous vs evergreen species). In addition to the expected negative correlation of Kl with drought tolerance, we found a strong, negative correlation between Kl and species’ shade tolerance. Across species, Ks and Kl were negatively correlated with wood density and positively with maximum vessel length. Consequently, drought and shade tolerance scaled similarly with hydraulic properties, wood density and leaf Dry matter content. We found that deciduous species also had traits conferring efficient water transport relative to evergreen species. • Hydraulic properties varied across species, corresponding to the classical tradeoff between hydraulic efficiency and safety, which for these Dry Forest trees resulted in coordinated drought and shade tolerance across species rather than the frequently hypothesized trade-off.
-
Seasonal variation in soil and plant water potentials in a Bolivian tropical moist and Dry Forest
Journal of Tropical Ecology, 2010Co-Authors: Lars Markesteijn, José Iraipi, Frans Bongers, Lourens PoorterAbstract:Abstract:We determined seasonal variation in soil matric potentials (ψsoil) along a topographical gradient and with soil depth in a Bolivian tropical Dry (1160 mm y−1 rain) and moist Forest (1580 mm y−1). In each Forest we analysed the effect of drought on predawn leaf water potentials (ψpd) and drought response (midday leaf water potential at a standardized ψpd of −0.98 MPa; ψmd) of saplings of three tree species, varying in shade-tolerance and leaf phenology. ψsoil changed during the Dry season and most extreme in the Dry Forest. Crests were drier than slopes and valleys. Dry-Forest top soil was drier than deep soil in the Dry season, the inverse was found in the wet season. In the moist Forest the drought-deciduous species, Sweetia fruticosa, occupied Dry sites. In the Dry Forest the short-lived pioneer, Solanum riparium, occupied wet sites and the shade-tolerant species, Acosmium cardenasii drier sites. Moist-Forest species had similar drought response. The Dry-Forest pioneer showed a larger drought response than the other two species. Heterogeneity in soil water availability and interspecific differences in moisture requirements and drought response suggest great potential for niche differentiation. Species may coexist at different topographical locations, by extracting water from different soil layers and/or by doing so at different moments in time.
-
light dependent leaf trait variation in 43 tropical Dry Forest tree species
American Journal of Botany, 2007Co-Authors: Lars Markesteijn, Lourens Poorter, Frans BongersAbstract:Our understanding of leaf acclimation in relation to irradiance of fully grown or juvenile trees is mainly based on research involving tropical wet Forest species. We studied sun–shade plasticity of 24 leaf traits of 43 tree species in a Bolivian Dry deciduous Forest. Sampling was confined to small trees. For each species, leaves were taken from five of the most and five of the least illuminated crowns. Trees were selected based on the percentage of the hemisphere uncovered by other crowns. We examined leaf trait variation and the relation between trait plasticity and light demand, maximum adult stature, and ontogenetic changes in crown exposure of the species. Leaf trait variation was mainly related to differences among species and to a minor extent to differences in light availability. Traits related to the palisade layer, thickness of the outer cell wall, and Narea and Parea had the greatest plasticity, suggesting their importance for leaf function in different light environments. Short-lived pioneers had the highest trait plasticity. Overall plasticity was modest and rarely associated with juvenile light requirements, adult stature, or ontogenetic changes in crown exposure. Dry Forest tree species had a lower light-related plasticity than wet Forest species, probably because wet Forests cast deeper shade. In Dry Forests light availability may be less limiting, and low water availability may constrain leaf trait plasticity in response to irradiance.
Margaret Kalacska - One of the best experts on this subject based on the ideXlab platform.
-
ecological fingerprinting of ecosystem succession estimating secondary tropical Dry Forest structure and diversity using imaging spectroscopy
Remote Sensing of Environment, 2007Co-Authors: Margaret Kalacska, G A Sanchezazofeifa, Benoit Rivard, Terry Caelli, Peter H White, Julio CalvoalvaradoAbstract:Abstract We evaluated the use of EO-1 Hyperion hyperspectral satellite imagery for mapping structure and floristic diversity in a Neotropical tropical Dry Forest as a way of assessing a region's ecological fingerprint. Analysis of satellite imagery provides a means to spatially appraise the dynamics of the structure and diversity of the Forest. We derived optimal models for mapping canopy height, live aboveground biomass, Shannon diversity, basal area and the Holdridge Complexity Index from a Dry season image. None of the evaluated models adequately estimated stem or species density. Due to the dynamic nature of the leaf phenology we found that for the application of remote sensing in Neotropical Dry Forests, the spectro-temporal domain (changes in the spectral signatures over time–season) must be taken into account when choosing imagery. The analyses and results presented here provide a means for rapid spatial assessment of structure and diversity characteristics from the microscale site level to an entire region.
-
secondary Forest detection in a neotropical Dry Forest landscape using landsat 7 etm and ikonos imagery1
Biotropica, 2005Co-Authors: J P Arroyomora, Margaret Kalacska, Julio Calvoalvarado, Arturo G Sanchezazofeifa, Benoit Rivard, Daniel H JanzenAbstract:We integrate Forest structure and remotely sensed data for four successional stages (pasture, early, intermediate, and late) of a tropical Dry Forest area located in the Sector Santa Rosa of the Guanacaste Conservation Area in northwestern Costa Rica. We used a combination of spectral vegetation indices derived from Landsat 7 ETM+ medium resolution and IKONOS high-resolution imagery. The indices (using the red and near-infrared bands) simple ratio and normalized difference vegetation index separated the successional stages well. Two other indices using mid-infrared bands did not separate successional stages as well. In a comparison of the successional stages with chronological age, there was no separability in the spectral reflectance among different age classes. Successional stages, in contrast, showed distinct groups with minimal overlap. We also applied a simple validation in another Dry Forest located in the Palo Verde National Park in the province of Guanacaste, Costa Rica, with reasonably good results. RESUMEN En este estudio, datos de campo y datos remotamente sensados son analizados para cuatro etapas sucesionales (pastos, temprano, intermedio y tardio) de un bosque seco tropical ubicado en el sector Santa Rosa del Area de Conservacion Guanacaste en el noroeste de Costa Rica. Utilizamos una combinacion de indices spectrales derivados imagenes satelitales, de mediana resolucion de Landsat 7 ETM+ y de alta resolucion de IKONOS. Los indices (usando las bandas de rojo e infrarojo cercano) de relacion simple (SR) e indice normalizado de diferencia vegetal (NDVI) separo bien las etapas sucesionales. Asi otros dos indices, usando las bandas de infrarojo medio no separaron las etapas sucesionales. En una comparacion de las etapas sucesionales con la edad cronologica, no existio separabilidad en la reflectancia espectral entre las diferentes clases de edad. Sin embargo, las etapas sucesionales mostraron grupos distinguibles con minima sobreposicion.Tambien aplicamos una simple validacion en otro bosque seco ubicado en el Parque Nacional Palo Verde en la provincia de Guanacaste, Costa Rica.
-
calibration and assessment of seasonal changes in leaf area index of a tropical Dry Forest in different stages of succession
Tree Physiology, 2005Co-Authors: Margaret Kalacska, Julio Calvoalvarado, G A SanchezazofeifaAbstract:A simple measure of the amount of foliage present in a Forest is leaf area index (LAI; the amount of foliage per unit ground surface area), which can be determined by optical estimation (gap fraction method) with an instrument such as the Li-Cor LAI-2000 Plant Canopy Analyzer. However, optical instruments such as the LAI-2000 cannot directly differentiate between foliage and woody components of the canopy. Studies investigating LAI and its calibration (extracting foliar LAI from optical estimates) in tropical Forests are rare. We calibrated optical estimates of LAI from the LAI-2000 with leaf litter data for a tropical Dry Forest. We also developed a robust method for determining LAI from leaf litter data in a tropical Dry Forest environment. We found that, depending on the successional stage of the canopy and the season, the LAI-2000 may underestimate LAI by 17% to over 40%. In the Dry season, the instrument overestimated LAI by the contribution of the woody area index. Examination of the seasonal variation in LAI for three successional stages in a tropical Dry Forest indicated differences in timing of leaf fall according to successional stage and functional group (i.e., lianas and trees). We conclude that when calculating LAI from optical estimates, it is necessary to account for the differences between values obtained from optical and semi-direct techniques. In addition, to calculate LAI from litter collected in traps, specific leaf area must be calculated for each species rather than from a mean value for multiple species.
Larry Royer - One of the best experts on this subject based on the ideXlab platform.
-
Allometric equations for predicting Puerto Rican Dry Forest biomass and volume
2009Co-Authors: Thomas J. Brandeis, Matthew Delaney, Larry Royer, Bernard R. ParresolAbstract:We used Forest inventory data, intensive tree measurement, destructive sampling in the field, and subsequent laboratory analyses to develop regression equations that estimate tree biomass, merchantable volume, and total volume for upland Forests in Puerto Rican subtropical Dry Forest. Most parsimonious and additive biomass equations for mixed, Dry Forest species were fitted to data from 30 destructively sampled trees, and most parsimonious volume equations were fitted for mixed species, Bucida buceras, and Bursera simaruba. Before undertaking this study, we were un- able to confidently estimate biomass and volume for these Forests despite having current, detailed Forest inventory data.
-
Development of equations for predicting Puerto Rican subtropical Dry Forest biomass and volume.
Forest Ecology and Management, 2006Co-Authors: Thomas J. Brandeis, Matthew Delaney, Bernard R. Parresol, Larry RoyerAbstract:Carbon accounting, Forest health monitoring and sustainable management of the subtropical Dry Forests of Puerto Rico and other Caribbean Islands require an accurate assessment of Forest aboveground biomass (AGB) and stem volume. One means of improving assessment accuracy is the development of predictive equations derived from locally collected data. Forest inventory and analysis (FIA) measured tree diameter and height, and then destructively sampled 30 trees from 6 species at an upland deciduous Dry Forest site near Ponce, Puerto Rico. This data was used to develop best parsimonious equations fit with ordinary least squares procedures and additive models fit with nonlinear seemingly unrelated regressions that estimate subtropical Dry Forest leaf, woody, and total AGB for Bucida buceras and mixed Dry Forest species. We also fit equations for estimating inside and outside bark total and merchantable stem volume using both diameter at breast height (d.b.h.) and total height, and diameter at breast height alone for B. buceras and Bursera simaruba. Model fits for total and woody biomass were generally good, while leaf biomass showed more variation, possibly due to seasonal leaf loss at the time of sampling. While the distribution of total AGB into components appeared to remain relatively constant across diameter classes, AGB variability increased and B. simaruba and B. buceras allocated more carbon into branch biomass than the other species. When comparing our observed and predicted values to other published Dry Forest AGB equations, the equation developed in Mexico and recommended for areas with rainfall >900 mm/year gave estimates substantially lower than our observed values, while equations developed using Dry Forest data from Forest in Australia, India and Mexico were lower than our observed values for trees with d.b.h. 30 cm. Although our ability to accurately estimate merchantable stem volume and live tree AGB for subtropical Dry Forests in Puerto Rico and other Caribbean islands has been improved, much work remains to be done to sample a wider range of species and tree sizes.
